CT characteristics of pheochromocytoma - Relevance for the evaluation of adrenal incidentaloma

Letizia Canu, Janna A W Van Hemert, Michiel Kerstens, Robert Hartman, Aakanksha Khanna, Ivana Kraljevic, Darko Kastelan, Corin Badiu, Urszula Ambroziak, Antoine Tabarin, Magalie Haissaguerre, Edward Buitenwerf, Anneke Visser, Massimo Mannelli, Wiebke Arlt, Vasileios Chortis, Isabelle Bourdeau, Nadia Gagnon, Marie Buchy, Francoise Borson-ChazotTimo Deutschbein, Martin Fassnacht, H Alicja Hubalewska Dydejczyk, Marcin Motyka, Wewlina Rzepka, Ruth T. Casey, Benjamin Challis, Marcus Quinkler, Laurent Vroonen, Ariadni Spyroglou, Felix Beuschlein, Cristina Lamas, William F Young, Irina Bancos, Henri J Timmers

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Background Up to 7% of all adrenal incidentalomas (AIs) are pheochromocytomas (PCCs). In the evaluation of AI, it is generally recommended to exclude PCC by measurement plasma free or 24h urinary fractionated metanephrines. However, recent studies suggest to abstain from biochemical exclusion of PCC in cases of lesions with computed tomography (CT) characteristics of an adrenocortical adenoma (ACA). Aim To determine the proportion of PCCs with ACA-like attenuation or contrast washout on CT. Methods For this multicenter retrospective study, two central investigators independently analyzed the CT reports of 533 patients with 548 histologically confirmed PCCs. Data on tumor size, unenhanced Hounsfield Units (HU), absolute percentage washout (APW) and relative percentage washout (RPW) were collected besides clinical parameters. Results Among the 376 PCCs for which unenhanced attenuation data were available, 374 had an attenuation of >10 HU (99.5%). In the two exceptions (0,5%), unenhanced attenuation was exactly 10 HU, which lies just within the range of ≤10 HU that would suggest a diagnosis of ACA. Of 76 PCCs with unenhanced HU >10 and available washout data, 22 (28,9%) had a high APW and/or RPW, suggestive of ACA. Conclusion Based on the lack of PCCs with an unenhanced attenuation of <10 HU, and the low proportion (0,5%) of PCCs with an attenuation of =10 HU, it seems reasonable to abstain from biochemical testing for PCC in AIs with an unenhanced attenuation ≤10 HU. The assessment of contrast washout, however, is unreliable to rule out PCC.
Original languageEnglish
JournalJournal of Clinical Endocrinology and Metabolism
Publication statusPublished - 31 Oct 2018


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